InGaAsP/InP quantum-well electrorefractive modulators with sub-volt Vpi

Advanced analog-optical sensor, signal processing and communication systems could benefit significantly from wideband (DC to > 50 GHz) optical modulators having both low half-wave voltage (Vpi) and low optical insertion loss. An important figure-of-merit for modulators used in analog applications is Tmax/Vpi, where Tmax is the optical transmission of the modulator when biased for maximum transmission. Candidate electro-optic materials for realizing these modulators include lithium niobate (LiNbO3), polymers, and semiconductors, each of which has its own set of advantages and disadvantages. In this paper, we report the development of 1.5-um-wavelength Mach-Zehnder modulators utilizing the electrorefractive effect in InGaAsP/InP symmetric, uncoupled semiconductor quantum-wells. Modulators with 1-cm-long, lumped-element electrodes are found to have a push-pull Vpi of 0.9V (Vpi*L = 9 V-mm) and 18-dB fiber-to-fiber insertion loss (Tmax/Vpi = 0.018). Fabry-Perot cutback measurements reveal a waveguide propagation loss of 7 dB/cm and a waveguide-to-fiber coupling loss of 5 dB/facet. The relatively high propagation loss results from a combination of below-bandedge absorption and scattering due to waveguide-sidewall roughness. Analyses show that most of the coupling loss can be eliminated though the use of monolithically integrated inverted-taper optical-mode converters, thereby allowing these modulators to exceed the performance of commercial LiNbO3 modulators (Tmax/Vpi ~ 0.1). We also report the analog modulation characteristics of these modulators.

[1]  C. Thirstrup,et al.  Refractive index modulation based on excitonic effects in GaInAs-InP coupled asymmetric quantum wells , 1995 .

[2]  O. Mitomi,et al.  A simple laterally tapered waveguide for low-loss coupling to single-mode fibers , 1993, IEEE Photonics Technology Letters.

[3]  I. Shubin,et al.  High-power intrastep quantum well electroabsorption modulator using single-sided large optical cavity waveguide , 2004, IEEE Photonics Technology Letters.

[4]  Quaternary quantum wells for electro‐optic intensity and phase modulation at 1.3 and 1.55 μm , 1989 .

[5]  B. Kolner,et al.  Intermodulation distortion and compression in an integrated electrooptic modulator. , 1987, Applied optics.

[6]  R.D. Esman,et al.  Photonic remoting of the receiver of an ultra-high dynamic range radar , 1998, 1998 IEEE MTT-S International Microwave Symposium Digest (Cat. No.98CH36192).

[7]  K. K. Loi,et al.  Low-loss 1.3-/spl mu/m MQW electroabsorption modulators for high-linearity analog optical links , 1998, IEEE Photonics Technology Letters.

[8]  Charles Cox,et al.  Figures of merit and performance analysis of photonic microwave links , 2004 .

[9]  P. Dapkus,et al.  Vertically coupled InP microdisk switching devices with electroabsorptive active regions , 2002, IEEE Photonics Technology Letters.

[10]  David A. B. Miller,et al.  Quantum‐confined Stark effect in InGaAs/InP quantum wells grown by organometallic vapor phase epitaxy , 1987 .

[11]  D. Miller,et al.  Quadratic electro‐optic effect due to the quantum‐confined Stark effect in quantum wells , 1987 .

[12]  Tadao Nagatsuma,et al.  Special Issue on Recent Progress in Microwave and Millimeter-wave Photonics Technologies , 2003 .

[13]  J. Abeles,et al.  Highly sensitive InP-based phase modulators based on stepped quantum wells , 2003, Conference on Lasers and Electro-Optics, 2003. CLEO '03..

[14]  Irwin L. Newberg,et al.  The first demonstration of an optically steered microwave phased array antenna using true-time-delay , 1991 .

[15]  J. Piprek,et al.  Slope efficiency and dynamic range of traveling-wave multiple-quantum-well electroabsorption modulators , 2004, IEEE Photonics Technology Letters.

[16]  F. Shepherd,et al.  10 Gbit/s, 1.56 mu m multiquantum well InP/InGaAsP Mach-Zehnder optical modulator , 1993 .

[17]  S. Forrest,et al.  Fabrication and analysis of high-contrast InGaAsP-InP Mach-Zehnder modulators for use at 1.55-μm wavelength , 1996, IEEE Photonics Technology Letters.

[18]  G. Betts,et al.  Direct-detection analog optical links , 1997 .

[19]  Yoshiaki Nakano,et al.  Field-induced optical effect in a five-step asymmetric coupled quantum well with modified potential , 1998 .

[20]  G. Li,et al.  Optical intensity modulators for digital and analog applications , 2003 .

[21]  E. Kapon,et al.  Low‐loss single‐mode GaAs/AlGaAs optical waveguides grown by organometallic vapor phase epitaxy , 1987 .

[22]  A. Napoleone,et al.  Sub-volt-V/sub /spl pi// InGaAsP electrorefractive modulators using symmetric, uncoupled quantum wells , 2003, The 16th Annual Meeting of the IEEE Lasers and Electro-Optics Society, 2003. LEOS 2003..

[23]  A. R. Clawson,et al.  Combined Franz-Keldysh and quantum-confined Stark effect waveguide modulator for analog signal transmission , 1999 .

[24]  Gary E. Betts,et al.  Techniques and Performance of Intensity-Modulation Direct-Detection Analog Optical Links , 1998 .

[25]  P. R. Ashley,et al.  High-performance Mach-Zehnder modulators in multiple quantum well GaAs/AlGaAs , 1994 .

[26]  D. Miller,et al.  Electric-field dependence of linear optical properties in quantum well structures: Waveguide electroabsorption and sum rules , 1986 .